Automatic telephone system



March 24. 1925.

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM 2 Sheets-Sheet l zz AH r N QDOMU D Q INVENTOR WIHFRED T POWELL BY A ATTORNEY dmsokw nom p and the} claims;

Patented Mai-.2 4, 1.925. I 1

UNITED. STATES PATENT orr cs.

wmrnnn 'r, rownnn,,.oi aocnnsrnn. New vonx, ASSIGNOR To THE SITROMBERG-V oAnLso TELEPHONE. MANUFACTURING COMPANY, or nocnns'rna. NEW YORK,

"A CORPORATION OF NEW'YORK.

AUTOMATIC, rEnErrroNE SYSTEM.

Application filed, September 13, 1919. 7 Serial No. 323,582.

T all whom/bitmap co Mam.

"Be it known that I, -WINFRED- fPownmi, a "citizen of; theUnitedASta-tes', residing at I Rochester, inthe county of Monroe, and .5 Stateof New Yorkfhave invented. certain new and useful Improvements in. Automatic Telephone Systems, of which the'following d te v switches for connecting any one of the same is a .fu1l', clear,' concise, and exact description@ 1O 1 This inventionlrelates to telephone systems, and more particularly to telephone systems employing [automatic switches for establishing connectionsbetween calling and called lines. i

In" such ;systems, especially where line finder switches'are employed, itis desirable to ha'veeach trunk common to a large num-v ber of lines. This arrangement, however,

hasjhad this great disadvantage in previous systems, since, inorder. to 1mm. trunk common to a large-number of lines, the finder switch individualto this trunk mustbe of large capacity and therefore the time required in; completing aconnection from a calling line to a trunk is unduly prolonged.

I In accordance with one feature of the present invention it is proposed to; .us'e finder switches of relatively small; capacity and provide two ofjthese switchesgfor-each trunk leading to the first numerical switch. in the system. In this arrangementimeans are provlded'whereby each group of lines is divided into two sub-groups, the lines of'one subgroup appearing at one finder sw tch, and

5 the lines of the second subgroup appearing only at 'the second finder switch, and other means are provided for determining which of the'finder switches will operate in establishingthe call. I

of the present invention, the :well known arrangement of fastan'd slow relays has been replaced by other means forcont'rolling the so-called change-over" from the primary to i the secondary operations ofthe-nuinerica'l SWlilGliBSzfiIld inthe control ofthe release ofsaid switches. i I Otherfeatures not specifically enumerated M will" appeanffroin the detailed description The drawings with left of Fig. Q diagrammaticalIy' represent a portion of a telephone system employingthe present invention. The portion above the Fig l placed at the.

heavy dotted line of Fig. 1 diagrammatical-. ly represents seven finder switches of which the-operatmg'circuit of the finder designated #1 IS shown completely, for connecting any one of seven idle trunks to anycalling line of the sub-group #1 of fifteen lines. The portion of the drawing below the heavy dot-- line also represents seven finder equipment for connecting one or the other of the two branches of the trunk to the numerical switch in which it terminates.

The finderswitches employed in this systemareof the uni-directional rotary type and may be similar in structure to the switch disclosed in the patent to Clement, #1,107,153. It will, however, be understoodthat the present invention is not limited to a unidirectional or a rotary type of switch,.but may'employ' a switch having ,group n and line selecting movements, such as the well known two movement switch of the'verticaland rotary type.

The numericalswitches employed in this system may be of a type substantially like that disclosed in the #815,176, patented Mar. 13th, 1906, when p v g o modified to operate in a twowire system. In accordance with an add tional feature .ing of the impulse springs on the last impulse of a series the shunting springs will alsobe opened, the purpose of which will appear" from the following description.

In the present invention the telephone lines are divided into groups of thirty lines each for the individual useof which seven The linesof a group are arbitrarily dividpatent to Keith et al conductor 15, brush 16 of the allotter, left ed into two sub-groups, the lines of one sub-group being multiplied at the contacts of seven finder switches, and the lines of the other sub-group being multiplied atv the contacts of the seven other finder switches. In this disclosure fifteen of the lines of the group terminate in sub-group #1, and the other fifteen lines of the group terminate in the sub-group #2. It will be understood, however, that the number of lines in a group as well as the number of trunks serving them, may be increased or diminished in number without departing from the present invention.

It is believed that this invention will best be understood by describing the method of establishing a connection from a calling substation indicated at A, to a called substation indicated at B. Let it be assumed that the calling line belongs to the sub-group #1. When the calling subscriber at A removes his receiver from itsswitchhook, a circuit is closed from ground, inner armature and bacl: contact of cut-off relay 5, contact 6 of the dial, through the substation circuits, back contact and armature of the cutoff relay, left hand winding of the line relay 7, left hand continuity spring and contact of this relay, conductor 8, outer armature and contact of the relay 9, left hand baclr contacts and armatures of the relays 10 and 11, and resistance to grounded battery. The line relay 7 attracts its armature, and at its'armat ure and continuity spring applies ground to the test conductor 12 to prevent the calling line being seized as a called line. At the left hand armature and continuity spring of the line relay 7 a substitute circuit for that just described is closed over conductor 17, and right hand winding of relay 10 to grounded battery. At the right hand armature and front contact or relay 7 an operating circuit for the motor magnet 13 of the finder is closed from ground, conductor 14:, armature, back contact and winding of the motor magnet 13,

hand winding, front contact and armature of relay 10, back contact and armature of relay 11, and through the resistance to gr unded battery.

Jude: the control of the circuit just described, the motor magnet 13 advances the brushes of the tinder until its test brush en counters the test contact 19 of the calling h e at which time a circuit is closed from round, inner right hand armature and front contact of the line relay, right hand winding of this relay, left hand winding of the cut-oil relay, test contact 19, test brush of the finder, conductor 520, controller brush 21, left hand winding, front contact and armature of relay 10, back contact and armature of relay 11. and resistance to grounded battery, to shunt magnet 13 and stop finder 1 on the calling line. The cut-off relay 5 is energized in this circuit and at its left hand armatures disconnects the line relay from the calling line. 'As soon as the relay 1() attracts its right hand armature, a circuit is closed from ground, a-llotter brush 26, conductors 27 and 28, winding of relay 24, through both windings in series of the differential relay 29, conductor 30, left hand back contact and arn'iature of release magnet 31, and resistance to grounded battery. The relay 2a is operated in this circuit, but the differential relay remains inactive as its opposing windings are energized. At its right hand armature and front contact the cut-off relay closes a locking circuit for itself through its right hand winding from grounded battery, holding contact 22 of the calling line, brush of the finder, conductor. 23, lower front contact and armature of relay 24, lower winding of relay 25 to ground, energizing relay 25.

As soon as the relays 2e and 25 are energized, the calling line is extended to a sensitive relay 32 and marginal relay 33 of the connector switch. These relays attract their armatures and at the left hand armature and front contact of the relay 33, a circuit is closed from ground, through the controller brush 3st, armature, back contact and winding of the motor magnet 35 of the controller, to grounded battery. The motor magnet interrupts its own circuit and advances the brushes of the controller into their second positions. A circuit is thereupon closed for energizing the relay 36, from grounded battery, through controller wiper 37 in its second position to ground. The relay 36 at tracts its armature, and at its lower armature closes a break point in therelease circuit of the connector switch, and at its upper-most armature and front contact, a circuit is closed through the innermost lower front contact, and Winding of relay'25 to grounded battery to maintain this relay enl ergized until disconnection. At its innermost upper armature and contact 40 of rel ay 36, a circuit is closed from ground over conductor 28, winding of relay 24, through both windings in series of the differential relay 29, conductor 30, back contact and armature of release magnet 31, and resistance to grounded battery. The relay 24' is thereby held energized during COllVGlSt-ttlOli to render the talking conductors continuous.

At the inner-most upper armature and con tact 4.1 of relay 36, ground is applied over conductor 42, allotter brush 13, and winding of relay 9 to grounded battery. The relay 9 is operated in this circuit, and at its outer armature and back contact interrupts the starting circuit of the finder switches of the group to prevent the starting of any finder. switch of the group during the operation o'fthe allotter. At the inner-most armature and frontcontact of the relay 9 a. multiple circuit is closed't'ro'm grounded battery, Winding, armature and back contact circuits, the motor magnet 44 of the allotter advances its brushes until an idle trunk is found, whlch' condition {is indicated by the absenceof ground potential onv a. conductor similar to 42.

Let it be assumed that the call had originated in that group of lines designated sub-group #2. Under this assumption on the "initiation of a ca-lh the line relay 45 will be operated in a circuit completed from ground, inner armature and back contact of its cut ofii relay 46, through the substation circuits, outer hack contact and armature of the cut-off relay, left hand Windwri m.

in continuit s rin andcontact of line relay45, conductor 4:6, armature and back contact of'relay 9,,back contacts and armavtures of relays '10 and '11, and resistance tov grounded battery. The line relay attracts its armatures and closes a substitute locking circuit for itself; throughits continuity springiand left hand ar1nature,condoctor 47, right hand windmgof relay 11 to grounded battery Relay 11 is energized in this circuit and attracts its armatures. At the left hand armature and front contactof relay 11, battery potential is applied through the allotter brush 21, conductors 20 and :48 to the test brush ofsthe allotted finder switch of sub-group. #2. The test conductor of thevcallinaline, as in the first case described, is characterizedhy the presence of ground potential, so that when the calling line is reached, cut-off relay a6 is operated and a locking, circuitj is closed through conductor 90. Assoon as the-relay 1 1 is actuated, a circuit is closed from ground, through its'right hand armature and front contact, controller brush49, coni ductor 50, right hand windingof the differential relay 29, conductor 30', .left hand back contact and armature of releasemagnet 31,

and resistance to grounded'battery. Since "only one Winding of the differential relay to I 29 is'energized, this relay will attract its armatures and the conductors 51jand 52 will be extended to the connector swltch.

At this time the circuit of switching relay;

24; is open, so that the branches 53 and {i l of the trunk are open at this time. In this,

as in the previous instance, theextension" of the calling line to the :connector energizes .the sensitive relay'32. and the marginal relay 33, and theoperation 'ofthis last men .i'ioned relay causes the motor magnet 35 of the controller (tomove the controller brushes into their second position; In this position the relay :36is1'ope rated for the purposes previously set forth. Now. 24; is short circuited.

The apparatus is now in condition to receive impulses from the impulse transmitter 3 wanted number. In operating his impulse transmitterthe calling subscriber first causes the shunt ng spring to engage the contacts 55 and 56, the latter contact engaging the ,shuntlng spring to short circuit the transmitter during the transmitting of impulses. In the. course of the operation of the impulse transmitter, the contact 6 will disengage its springa number of times corre sponding to the first digit of the wanted number. hen thecontact 6 disengages its impulse spring, resistance 57 is then in chided in the signaling circuit extending serially through. the sensitive relay 32 and the marginal relay The relay 32 is so designed that it will not release in series with the resistance 57, but the marginal relay 33 is designed to deenergize when in series with the last mentioned resistance. It will therefore'be seenthat each time that the impulse springs are operated, the resistance 57'is included in the signaling circuit and that the marginal relay 33 deenergizes once for each impulse of the series corresponding to the digit of the wanted number. In response to each operation of the marginal relay 33, a circuit is closed for the primary motor magnet PM of the connector from grounded battery, win-ding of this magnet, controller wiper 58 in its second positioin'baclr contact and armature of relay 33 to ground. In response to each retraction ofthe armature of the marginal relay 33, the primary motor magnet advances the brushes of the connector one step in its primary or group selecting movement. At the close of the tens series of impulses, the signaling circuit is interrupted since the impulse and shunting springs are so adjusted that they are simultaneously 'opened'at the time that the last impulse is transmitted I At this time both the sensitive relay32 and the marginal relay 33 are tive relay 32, back contact and arn'iature of the marginal relay 33 to ground. The motor magnet 35 of the controller is energized in thls circuit, and when the impulsetrans- ,mitter at the calling substation has been restored to normal, the signaling circuit serially including the relays 32 and 33 is again completed, causing these relays to attract their armatures. scribed for the motor magnet is interrupted and the controller wipers are moved into their third position. 1

At this time the calling subscriber operates his impulse transmitter to send inipulses corresponding to the units digit of the wanted number. The n'iarginal relay 33 again vibrates its armature and thereby closes a circuit from ground, its armature and back contact, controller brush 58 in its third position, winding of the secondary motor magnet SM to grounded battery. Under the control of this circuit the secondary motor magnet advances the brushes of the connector in their line selecting movement. At the close of the units series of impulses, the signaling circuit is again momentarily interrupted so that relays and 33 again simultaneously retract their armatures. The motor magnet 35 of the controller is again operated in a circuit now traced from grounded battery, winding of the motor magnet, conductor 60, armature and front contact of the secondary motor magnet SlVI, right hand armature and back contact of relay 32, back contact and armature of relay 33 to ground. The signaling circuit is almost immediately completed, so that the relays 32 and 33 again attract their armatures. The circuit just described for the motor magnet 35 of the controller is interrupted and this magnet moves the controller brushes into their fourth or testing position.

If the called line is idle this condition will be indicated by the presence of full battery potential on its test contact 61, so that when the controller brush 62 moves into its fourth position a circuit is closed for the relay 63 from ground, winding of this relay, controller brush 62, connector brush 64, test contact 61, resistance corresponding to the cut-oli' relay of the wanted line to grounded battery. WVhile the controller wipers were in position three, the marginal slow-releas ing trip relay 65 was energized over a circuit traceable from grounded battery, through the ringing machine generally designated 66, lamp 67, winding of the trip relay 65, controller Wiper 68 in its third position to ground. The trip relay 65 is energized, and since it was slow to release it holds its armatures attracted even after the controller wipers have moved into position four. Nith the relays 63 and 65 thus operated, a circuit is closed from ground, left hand armature and front contact of relay 63, armature and front contact of relay 65, conductor 69, controller wiper 34, armature, back contact and winding of the motor magnet 35 of the controller to grounded battery.

The circuit just de- Shortly after the motor magnet is energized, the trip relay 65 retracts its armature, interrupting the operating circuit of the motor magnet 35 and causing it to more the controller wipers into their fifth or ringing and talking positions. The relay 63 is now maintained energized in a circuit extending from ground, winding of this relay, conductor 72, controller wiper 34, armature, back contact and winding of the motor magnet 35 to grounded battery. It should here be stated that the wipers an and 62 of the controller are so adjusted that wiper 34. engages its fifth contact shortly before the wiper 62 disengages its fourth contact thus insuring that the relay will be maintained energized in positions at and 5 of the con troller wipers.

In position 5 of the controller ringing current is transmitted to the called substation over a circuit traced from grounded battery. resistance, through the ringing machine 66, lamp 67, ringing trip relay 6:3, controller wiper 68, right hand armature and front contact of relay 63, inner-most back contact and armature of relay 73, connector brush 74, through the called substation circuits and bell, connector brush 75, uppermost armature and back contact of relay 73, back contact and armature of trip relay 65, front contact and armature of relay 63 to ground. When the called party at sub station B responds by removing his receiver from its switchhook, the trip relay 65 is energized and removes the short circuit which existed about the upper winding of the switching relay 73. This switching relay 73 is thereupon actuated in a circuit similar to the ringing circuit, except that the upper winding of the relay 73 is included and the circuit is completed over conductor 7 6 to ground at the front contact and armature of relay 63. Relay 7 3 when operated locks itself energized in a circuit including its lower winding, conductor 82 and off normal sprin and contact 81 to grounded battery.

Talking battery is supplied to the calling party through the windings of the relays 32 and 33, and to the called party through the windings of the impedance coil 78.

Let it be assumed that the called party is busy when the test brush 64 of the connector engages its test terminal 61. In this event, its terminal 61 will be characterized by reduced battery potential, so that the relay 63 will not be energized even when the controller wiper 62 is in position four. The busy signal is then transmitted to the calling subscriber from the ringing machine 66, lamp 67, ringing trip relay 65, side switch wiper 68 in its fourth position, eonductor 79, through the condenser and thence to the calling substation.

Ill!

The release of i the connector switch is controlled in part by a; constantly operating interrupter shown at the bottom of Fig.

2. This interrupting device maybe ofany form in which the contact/s83 and 84 engage their springs at predeterminedtime intervals; As shown this device consists of a shaft mountedffor continuous rotation at.

constant speed which has, secured to it two cam disks so disposed that a circuit will not be closed thro'ughcontact 83 and its spring untila predetermined interval attercont'act 8st engaged its spring. r I c When the calling subscriber restores his receiver to its switchhook, the relay32 dee'nergizes and closes a circuit from ground, through its outer" left hand "armature and contact, lower front contact and armature of relay 36, winding of relay 80', its continuity springand contact, and contact 84 and its spring, andresistance to g'rounded battery. Relay-80 is cne'rgi'ze'd in this circuit and attracts its armatures. fAt its innet arm'ati'lre and continuity springit closes 'a locking' circuit for itself from grounded battery to ground at the-onter'left hand airmature of relay '32 over'the remainder of the circuit previousl described It should here b'e'noted that the relay 32 deenergizes momentarily at the conclusion ofeach series ofimp ulses, but that it almost immediately is again ener ized so that if relay 80 is energiz'ed at thi'sftime, this'int'erval will not be long enough[for the circuit of the release I magnet 31 to-be closed at interrupter 83.

However, at the termination ofthe call, re- 1a'y32 will be deenergized for a relatively long time-after therelay 80 has been energiz'ed, so that contact 83 will engage its spring. and close. a circuit from ground, through the upper front contact: and arma ture of relay r80, contact and 'continuity spring-and right hand winding of the release magnet 31 to grounded battery; The release magnet 131 is -thusenergized and closes a locking circuit" from ground, its

innerleft hand armature-front contact and winding, off. normal s ring and contact 81, resistance to grounded battery; At the outer lefii rhandparmature and back? contact of release magnet'31,the conductor 30 is interrupted to prevent thc fclosure of trunk conducto rs 51 and 52 or53f and 54 to the connector during the release of this switch. At the right hand 1 armature and front tion permitting the relay 36':to deenergize, and this relay in turn removes the guarding potential from the trunk used and releases relays 24 and 25. When relay 24 deenere gizes, the holding conductor 23 is opened causing the cut-off relay 5 to reconnect the line relay 7 to itstelephone line.

It will be understood that although onlya' connector switch has been disclosed, in a larger system one or more selector switches operating in a manner similar to the connector switch hereini shown, will be used in establishing connections; r

What I claim is: i 1; In a telephone system, telephone'lines,

trunk lines for extending said telephone lines, each trunk terminating at one end in-a numerical switch, and at its other end in two mechanically independent non-numerical switches a single allotter for said trunk lines for assigning the same for use and means for detemmnmg which .ot' said nonnumerical switches will connect said trunk.

line to a calling telephone line.

2. In a telephone system, groups of telephone lines, a plurality of trunks individual to each group of telephone lines, a single allotter assigning trunks foruse, each of said trunks terminating in two mechanically independent non-numericfl switches, and

means for determining'which of said nonline to an assigned trunk. I s I 3;. In a telephone system, groups of telephone lines, a plurallty of trunks individnumerical switches, will con-nect a calling nail to each group of telephone lines, a single allotter for assigning the trunks of a group for use in succession, each of said trunks terminating in two mechanically independ ent non-numerical switches, and means for determining which of .said non-numerical switches will connect aFca1l1ng-l1ne to an assigned trunk.

'4. In a telephone system groups of telephone lines, a plurality of trunks individual to each group of telephone lines,a single progressively "movable allotter for assigning the trunks of a group in succession, each of said trunks terminating in two mechanically I independent non-numerical switches, and means for determining which of said non-numerical switches will connect a calling line to an assigned trunk.

5. In a telephone system, groups of lines divided into sub-groups, trunks individual to each group-of lines, each trunk having a branch individual to each sub-group of lines, a separate automatic switch for each branch, a single allotterindividual to each group of trunks for assigning the same for use and means controlled by the sub-group in which a calling line is located for extendme; one of said branches ofa trunk to a calling line and for rendering the other branches of said trunkv ineffective.

rendering the other branches of saidtrunk ineffective.

'7. In a telephone system. a group of telephone lines divided into sub-groups, a trunk line individual to said group of lines, said trunk having a branch individual to each subgroup of lines, mechanically independ ent switches in which said branches terminate, a switching relay controlling a break point. in each branch of said trunk, means controlled by the initiation of a call in'one of said subgroups for extending a calling telephone line to one of the branches of said trunk and for operating the switching relay of the connected branch;

8. In a telephone system, a group of telephone lines divided into sub-groups, a trunk individualto said group of lines said trunk having a branch individual to each subgroup or lines, mechanically independent switches in which said branches terminate, a

diiierential relay for rendering continuous one or another of said branches, and means controlled by the initiation of a call on one of said telephone lines for extending said line to said trunk by way of one of said branches and for controlling the operation of said differential relay.

9. In a telephone system, an incoming line, a plurality of outgoing lines,"an auto matic switch operating through group and line selecting movements for selecting a desired outgoing line, a controlling circnit for said automatic switch serially including two sides of the incoming line'in series, means whereby said automatic switch is adjusted in response to current variations in said controlling circuit while said circuit is closed, means controlled by the opening of said controlling circuit for causing saidautoma-tic switch to change from its group to its line selecting movement and a mechanical timing device common to a plurality of switches for controlling the release of said automatic switch.

10. In a telephone system. an incoming line, a plurality of outgoing lines, an automatic switch operating through group and line selecting movements to extend said incoming line to a desired outgoing line, a controlling circuit for said automatic switch serially including two sides of said incoming line in series, two relays which are unequally sensitive including in said controlling circuit, means for causing current variations in said controlling circuit while it is continuous whereby one of said relays causes said automatic switch to be moved through its group and line selecting movements, means for interrupting said controlling circuit to govern the other relay, means controlled thereby for causing said automatic switch to change from its group to its line selecting movement, releasing mechanism for said switch. and timing mechanism common to a plurality of lines, cooperating with said last mentioned relay to operate said releasing mechanism. 7,

11. In a telephone system, incoming circuits, an outgoing circuit having branches, a separate non-numerical switch having no fixed normal position individual to each one of said branches, and means for operating one or the other, of said switches to extend said outgoing circuits to one of said incoming circuits.

12. In a telephone system, incoming cir cuits, a plurality of outgoing circuits, an allotter for assigning an outgoing circuit for use, each of said outgoing circuits having branches each of which is provided with a non-numerical switch having no fixed normal position, and means for operating one or the other ofsaid non-numerical switches of an allotted outgoing circuit for extending the same to one of said incoming circuits.

13. Ina telephone system, incoming circuits, a plurality of outgoing circuits, at rotary allotter for assigning an outgoing circuit for use, each of said outgoing circuits having'branches each of which is provided with a non-numerical switch having no fixed normal position, and means for operating one or the other of said non-numerical switches of an allotted outgoing circuit for extending the same to one of said incoming circuits.

14:. In a telephone'system, a plurality of automatic switches, each automatic switch having sets of terminals arranged in a semicircular terminal bank and a set ofbrushes for engagement with said set of terminals; means including a motor magnet forad vancing a set of said brushes'progressively over its associated terminal bank; a plurality of telephone lines terminating in said terminals; a trunk circuit terminating in each set of switch brushes, means "for allotting an idle trunk for use; a cut-off relay in dividual to each telephone line; said cut-off relay being provided with two sets of springs arranged to be closed on its deenergization; a conductor for connecting each cut-off relay tothe-multiple terminals in dividual to its telephone line appearing at said automatic switches; aline relay for each telephone line provided with a set of springs arranged to he closed on its operathrough'its winding, through the two sets of springs of the cut-off relay and both sides of the calllng telephone line 111861185 a 01rcuit for the" motor magnet of the switch associated with the allotted trunk, said circuit extending through a set of springs of the line relay; through the Winding of said motor magnet and through said allotting means; a stepping circuit in shunt of the operatingcircuit of the motor magnet extending through a brush of the allotted switch,

a terminal of the calling line and through the operated springs ot'said line relay, said last described circuit functioning to stop the operation of the motor magnet; and means responsive to the location of the calling line for maintaining the cut-off relay opera-ted.

1.5. In a telephone system a group of telephone lines divided into sub-groups, trunk lines individual to said group of lines, each trunk having a branch individual to each sub-group of lines, mechanically independ ent hunting switches in which each of said branches terminates, means controlled by the initiation of a call in'one of said sub-groups for causing the switch of one of said branches to hunt for the calling line and means for preventing more than one switch hunting in a group at anyone time.

' In witness whereof, I hereunto subscribe my name this 12th day of September A. D. 1919.

WINFRED T. POWELL. 

